The clinical value of [18F]fluoro-dihydroxyphenylalanine positron emission tomography in primary diagnosis, staging, and restaging of neuroendocrine tumors

The study was set up to determine the clinical value of dihydroxyphenylalanine positron emission tomography-computed tomography ([18F]DOPA PET-CT) in patients with neuroendocrine tumors (NETs). Eighty-two patients with suspected/known NET were imaged with PET(-CT) using [18F]DOPA. Patients were divided into two groups: primary diagnosis/staging and restaging of disease. All patients without previous diagnosis of NET had biochemical proof of disease. The diagnostic accuracy of PET was assessed by comparing the histopathology and clinical follow-up. The overall accuracy of [18F]DOPA PET was 90%. In patients having PET for primary diagnosis/staging (n=32), the accuracy of PET was 88%, and for restaging 92% (n=61). The mean s.d. sizes of primary and metastatic lesions detected by PET were 26±11 and 16±9 mm respectively. In organ-region-specific analysis, the sensitivity and specificity were 100% in the primary diagnosis of pheochromocytoma (n=16) and metastases were found in all cases with recurrent disease (n=5). The accuracy for NET of gastrointestinal tract was 92% in restaging (n=24). For the NETs located in the head–neck–thoracic region (n=19), the overall accuracy of PET was 89% including 12 cases of recurrent medullary thyroid cancer with a sensitivity of 90%. In analysis of patients with biochemical proof of disease combined with negative conventional imaging methods, PET had positive and negative predictive value of 92% and 95% respectively. [18F]DOPA PET-CT provided important additional information in the diagnosis of pheochromocytoma and restaging of known NET. Both in primary diagnosis and in patients with formerly known NET and increasing tumor markers, [18F]DOPA PET-CT is a sensitive first-line imaging method.